Polyester-based resins typified by polyethylene terephthalate (PET) have been widely used in containers such as bottles for storing various beverages, detergents, cosmetics, and the like because each of the resins is excellent in, for example, heat resistance, transparency, and mechanical strength, and its surface is hardly flawed. Meanwhile, polyolefin-based resins such as polyethylene and polypropylene have been widely used as materials of which various containers are constituted because of their excellent moldability, low prices, and the like.
In addition, various plastic containers having additionally excellent characteristics provided by the following procedure have also been proposed: those resins are arbitrarily combined so that each of the containers may have a multilayer structure. For example, a multilayer plastic container having the following layer constitution has been conventionally known (see, for example, Patent Documents 1 and 2) : (1) a polyester-based resin outer layer, (2) an adhesive resin layer, and (3) a polyolefin-based resin layer are laminated in the stated order from the outer surface side of the container.    Patent Document 1: JP 06-79842 A    Patent Document 2: JP 06-106606 A
However, a multilayer plastic container having such a layer constitution involves differences in molding characteristics such as a melt resin viscosity among a polyester-based resin, an adhesive resin, and a polyolefin-based resin of which the container is constituted. Therefore, upon production of, for example, a hollow container by blow molding after the formation of a multilayer parison, an external appearance failure such as a grain pattern or a ripple pattern may occur in the polyester-based resin outer layer at the surface of the container or in an interface between adjacent layers of the container. In addition, the hue of the container becomes uneven, so a hue failure such as the production of a stripe-like pattern occurs. Accordingly, it has been unable to realize a multilayer plastic container having an excellent external appearance such as a container having a high-gloss, deep, evenly metallic color tone.
In addition, a reduction in roughness of a surface in a die intended for smooth finish of the surface of the container involves the emergence of an air trap at the time of the molding of the container (phenomenon in which an untransferred portion of a die shape remains owing to the incorporation of air between the die and the surface of the molded article). As a result, the following problem arises: a molding failure such as a partial concavoconvex occurs at the surface of the container.